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11.
R SAPRA S K DHAKA V PANWAR R BHATNAGAR K PRAVEEN KUMAR Y SHIBAGAKI M VENKAT RATNAM M TAKAHASHI 《Journal of Earth System Science》2011,120(5):807-823
Relationship of outgoing long-wave radiation (OLR) with convective available potential energy (CAPE) and temperature at the 100-hPa pressure level is examined using daily radiosonde data for a period 1980–2006 over Delhi (28.3°N, 77.1°E) and Kolkata (22.3°N, 88.2°E), and during 1989–2005 over Cochin (10°N, 77°E) and Trivandrum (8.5°N, 77.0°E), India. Correlation coefficient (R xy) between monthly OLR and CAPE shows a significant (~???0.45) anti-correlation at Delhi and Kolkata suggesting low OLR associated with high convective activity during summer (seasonal variation). Though, no significant correlation was found between OLR and CAPE at Cochin and Trivandrum (low latitude region); analysis of OLR and temperature (at 100-hPa) association suggests that low OLR peaks appear corresponding to low temperature at Delhi (R xy~ 0.30) and Kolkata (R xy ~ 0.25) during summer. However, R xy between OLR and temperature becomes opposite as we move towards low latitudes (~8°–10°N) due to strong solar cycle influence. Large scale components mainly ENSO and quasi-biennial oscillaton (QBO) that contributed to the 100-hPa temperature variability were also analyzed, which showed that ENSO variance is larger by a factor of two in comparison to QBO over Indian region. ENSO warm conditions cause warming at 100-hPa over Delhi and Darwin. However, due to strong QBO and solar signals in the equatorial region, ENSO signal seems less effective. QBO, ENSO, and solar cycle contribution in temperature are found location-dependent (latitudinal variability) responding in consonance with shifting in convective activity regime during El Niño, seasonal variability in the tropical easterly jet, and the solar irradiance. 相似文献
12.
On an experimental basis, observations were made with various geophysical methods to locate the ancient gold workings in Kolar Gold Fields, Kolar, India. The results of experimental surveys indicated that two-electrode resistivity surveys with two spacings followed by limited trenching would be able to locate about 70 percent of the ancient workings, at 55-60 percent of the cost of conventional trenching. 相似文献
13.
Understanding the fundamental issues related with the effect of shear velocity on frictional characteristics at the interface
of rock surfaces is an important issue. In this paper, strain-rate dependence on friction is investigated in relation to sliding
behaviour under normal load. The phenomenon of stick-slip of granite and shaly sandstone with a tribometer at constant rate
of strain under normal loads was observed. 相似文献
14.
Abstract The Seddon speed formula expressed mathematically as c = dQ/dA (or alternatively, as c = (1 + m)uo; where Q is the discharge, A is the area of cross-section, c is the wave speed, uo is the normal flow velocity, and m is a dimensionless parameter) is revisited in the context of elasticity and thermodynamics. Its link with the linearized solution of St Venant's equations for wave celerity, which does not appear to have been reported in the hydrological literature, is established. The rating exponent m is shown to be equivalent to the dimensionless relative celerity and is found to be the ratio of two specific heats, viz. cp and cv which are the specific heats at constant pressure and volume, respectively. The use of the parameter m as a complex variable helps describe shallow wave characteristics, the damping capacity of a wave, and the mechanism of occurrence of the hysteretic phenomenon. The damping capacity is found to describe the magnitude of wave subsidence, whereas the hysteresis also describes the speed of subsidence. 相似文献
15.
16.
One-dimensional unsteady solute transport along unsteady flow through inhomogeneous medium 总被引:1,自引:0,他引:1
SANJAY K YADAV ATUL KUMAR DILIP K JAISWAL NAVEEN KUMAR 《Journal of Earth System Science》2011,120(2):205-213
The one-dimensional linear advection–diffusion equation is solved analytically by using the Laplace integral transform. The
solute transport as well as the flow field is considered to be unsteady, both of independent patterns. The solute dispersion
occurs through an inhomogeneous semi-infinite medium. Hence, velocity is considered to be an increasing function of the space
variable, linearly interpolated in a finite domain in which solute dispersion behaviour is studied. Dispersion is considered
to be proportional to the square of the spatial linear function. Thus, the coefficients of the advection–diffusion equation
are functions of both the independent variables, but the expression for each coefficient is considered in degenerate form.
These coefficients are reduced into constant coefficients with the help of a new space variable, introduced in our earlier
works, and new time variables. The source of the solute is considered to be a stationary uniform point source of pulse type. 相似文献
17.
NAND L SHARMA JAGDISH C KUNIYAL MAHAVIR SINGH PRIYANKA SHARMA KESAR CHAND AJAY KUMAR NEGI MANUM SHARMA HARINDER KUMAR THAKUR 《Journal of Earth System Science》2011,120(2):281-290
The concentration of ultrafine aerosol particles of aitken and nucleation mode having size in the range of 1–20 nm was monitored
with water-based Condensation Particle Counter. The monitoring was carried out from midnight-to-midnight in every alternate
day on a fortnightly basis to represent summer, monsoon and winter (autumn) seasons of 2008 at Mohal (1154 m amsl) and Kothi
(2530 m amsl) in Kullu-Manali area of the northwestern Himalayan region of India. The results indicate that diurnal pattern
has faint bimodal structure with two peaks, one in morning and the other in evening at both the sites but it is not as distinct
as found in plains. There is rather a constant particle density pattern of large magnitude consistent with vehicular movement
from morning till evening. The monthly 24 h average particle density gradually picks up from January, increases rapidly in
summer months and then decreases in monsoon season at Mohal but at Kothi it keeps on rising from April to October with a slight
more increase in September. The particle density is more in summer than in monsoon season at Mohal, a trend opposite to plains.
It may be due to the development of warm thermal layer on valley floor while a cold layer develops along snowy hilltops in
winter leading to convection of fine particle up the slopes of valley during daytime. At Kothi, the trend is same as it is
in continental plains but opposite to Mohal. The relatively more value of particle density in September and October at both
the sites may be due to month long International Kullu Dussehra fair in the valley. The vehicular survey conducted agrees
well with entire study period averaged diurnal variations and monthly 24 h averaged value of fine particle density. The average
value of ultrafine particle density at each hour of a day for entire study period is 20369 ± 1230 Ncm − 3 and 14389 ± 1464 Ncm − 3 at Mohal and Kothi sites, respectively. The comparison with earlier results shows a significant increase indicating impact
of vehicular onslaught on pure air of this hilly region. 相似文献
18.
19.
20.
This study characterizes the black carbon in Agra, India home to the Taj Mahal—and situated in the Indo-Gangetic basin.The mean black carbon concentration is 9.5 μg m~(-3)and, owing to excessive biomass/fossil fuel combustion and automobile emissions, the concentration varies considerably. Seasonally, the black carbon mass concentration is highest in winter, probably due to the increased fossil fuel consumption for heating and cooking, apart from a low boundary layer. The nocturnal peak rises prominently in winter, when the use of domestic heating is excessive. Meanwhile, the concentration is lowest during the monsoon season because of the turbulent atmospheric conditions and the process of washout by precipitation. The ratio of black carbon to brown carbon is less than unity during the entire study period, except in winter(December). This may be because that biomass combustion and diesel exhaust are major black carbon contributors in this region, while a higher ratio in winter may be due to the increased consumption of fossil fuel and wood for heating purposes. ANOVA reveals significant monthly variation in the concentration of black carbon; plus, it is negatively correlated with wind speed and temperature. A high black carbon mass concentration is observed at moderate(1–2 m s~(-1)) wind speed, as compared to calm or turbulent atmospheric conditions. 相似文献